Date   : Wed, 29 Sep 2004 14:15:49 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: FW: BBC Master Compact cabling info

Bill Keesing <zz9pluralzalpha@...> wrote:
> and a ROM in the frontmost socket (IC49) with a sticker that reads
> 
> 537X
> 0004
> 
> Could someone please elighten me as to what this ROM is.
 
That's probably the Master Compact 64K system ROM.
 
> I can see a WD1772 chip just below the disc interface so I am assuming the
> machine is ready to take a disc drive. All I need is the ADFS ROM,
> correct?
 
If it is a Master Compact, ADFS is already in the system ROM. By default,
the Compact has: BASIC ADFS UTILS MOS
 
The ROM sockets are laid out as:
 
  ROM 3
  ROM 2
  ROM 8
  ROM 0,1
  ROM 13,14,15,MOS
 
> has an electronic copy could they please email them to me. I am after the
> pinouts for the power supply and the disc interface.
 
Power supply: Centre +9v, Outer 0v. BUT CHECK THIS as I may have got this
wrong. Check the PCB tracking to confirm this. I have replaced the PSU
socket on my Compacts with a connector that I plug a disk drive PSU
connector into.
 
Disk Drive:
 1       ~INDEX
    14       0v
 2       ~DS0
    15       0v
 3       ~DS1
    16       0v
 4       ~DS2
    17       0v
 5       ~MOTOR ON
    18       0v
 6       ~DIR
    19       0v
 7       ~STEP
    20       0v
 8       ~WRDATA
    21       0v
 9       ~WRGATE
    22       0v
10       ~TRK0
    23       0v
11       ~WRPROT
    24       0v
12       ~RDDATA
    25       0v
13       SIDE
 
You can connect a standard 34-way disk drive lead by omitting pins 1-7,
pin 8 onwards goes to the 25D pin 1 onwards, and pin 33-34 are omitted:
 
              1
              to
              7
       1 ---->8
  25D  to     to  34W IDE
       25---->32
              33
              34
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
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